US2172261A - Pressure control pneumatically operated switch - Google Patents

Description

Sept. 5, 1939. RIPPL. 2,172,261

PRESSURE CdNTROL PNEUMATICALLY OPERATED SWITCH Filed Jan. 15, 1957 2 Sheets-Sheet 1 COMPRESSED FLUID SOURCE CHARLES H. RIPPL.

BY 5 z 2/ I M ATTRNEY.

Sept. 5, 1939. c. H RIPPL 2,172,261

a m HEP" s PRESSURE CONTROL PNEUMATICALLY OPERATED SWITCH Filed Jan. 13, 19257 2 Sheets-Sheet 2 FIGS.

INVENTOR. CHARLES H. RIPPL.

ATTORNEY.

Patented Sept. 5, 1939 UNITED STATES PATENT OFFIQE PRESSURE CONTROL PNEUMATICALLY OPERATED SWITCH Charles H. Rippl, Clevel The Clark Controller and, Ohio, assignor to Gompany, Cleveland,

7 Claims.

This invention relates to fluid pressure operated apparatus.

While the fluid pressure apparatus of my invention may have various applications, it is particularly applicable to the operation of an electric switch for timing the duration of the electric current at the welding electrodes of a welding gun or device or of a welding machine.

It is among the objects of the invention:

To provide an improved fluid pressure operated apparatus;

To provide a pneumatically operated apparatus comprising improved means for operating an electric switch to time the duration of the current controlled thereby;

To provide an apparatus adapted in an improved manner to be operated by fluid pressure under the control of a welding machine using electric current, to control an electric switch for timing the duration of the welding current;

To provide a pneumatically operated apparatus for operating a timing switch, and having improved means to adjust the time interval dur ing which the switch remains closed;

To provide an improved pneumatically operated servo-motor device adaptable to operate a reciprocatory apparatus;

To provide an improved unitary valve construction for controlling the operations of a pneumatically operated device.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed in the following description taken in connection with the accompanying drawings in which:

Fig. l is a front elevational view of an embodiment of my invention and showing its use in connection with a welding gun and an electric switch for timing the electric current supplied to the gun;

Fig. 2 is a longitudinal sectional view to an enlarged scale taken from the plane 2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view of parts shown in elevation in Fig. 2;

Fig. 4 is a cross-sectional view taken from the plane 4 -4 of Fig. 1;

Figs. 5 and 6 are views generally similar to Fig. 2 but with parts broken away and with operative parts in different positions;

Fig. '7 is a longitudinal sectional view of a part of Fig. 2 taken from the plane l'l of Fig. 2;

Figs. 8 and 9 are respectively cross sectional views taken from the planes 8-8 and 99 of Fig. 2;

Fig. 10 is a fragmentary View illustrating in modified form one of the operating elements of Figs. 2, 5 and 6;

Fig. 11 is a top plan view of a part of the device of Fig. 2 taken from the plane ll-H of Fig. 2;

Fig. 12 is a developed view showing in one figure, parts shown separately in Figs. 2 and 7.

Referring to the drawings, I have shown at I a panel preferably of insulating material upon which a pair of stationary contacts 22 are mounted. A rectangular shaft 3 having round ends 4 is oscillatably supported in brackets 5 and 5A and has a rectangular tube of insulation 6 thereon upon which are clamped movable switch arms 'l'| carrying contacts 8-8 which are moved to engage and disengage the stationary, contacts 2-2 when the shaft is oscillated in a manner to be described. When the contacts 2 and 8 are engaged, an electric circuit is made from supply mains 9-9 through the engaged contacts to wires it-Hi connected to the stationary electrode l i and the movable electrode l2 of a welding gun shown generally at l3 whereby when the movable electrode |2 moves, work to be welded I4 will be clamped between the electrodes and current may be caused to flow therethrough to effect a weld.

The construction of the gun l3 comprises no essential part of the present invention. In a form shown, a head l5 supports the stationary electrode 1 l, and the cylinder it on the head has a piston I! normally held in one end of the cylinder by a spring 18 and arranged to be moved toward the other end of the cylinder when air is admitted to the cylinder through a duct l9 and the movement of the piston I! being communicated to the movable electrode I2 by a piston rod 20.

To operate the gun, compressed air or other fluid under pressure is conducted from a source 2| through a conduit 22 to a valve cylinder 23 in the gun in which reciprocates a gun valve 2d. The valve is normally constrained by a valve spring 25 to take up the position illustrated in which flow from the conduit 22 is obstructed. When a button 25 on the valve 24 is depressed against the force of the spring 25, fluid under pressure from the conduit 22 may flow around a neck 21 of the valve to the duct 19 to operate the gun. Upon releasing the button, air from the gun is discharged through the duct l9 and around the neck 2'! of the valve and exhausted out to atmosphere at a port 98.

Communicating with the duct l9 between the valve 24 and the gun cylinder it is a conduit 28 through which fluid under pressure may flow to operate the switch contacts above referred to by means presently to be described.

By the switch operating means to be described, the switch is caused to close and remain closed for a time interval and then is caused to open, thus sending through the electrodes ll--i2 an electric current of predetermined time duration suitable to make the weld and the switch is closed after the pressure engagement of the electrodes H-l2 on the work l9 has been effected by the gun.

Rigidly clamped upon the rectangular portion of the shaft 3 is an arm 29, one suitable arrangement for clamping it being shown in Fig. 3 and comprising a block 38 recessed to fit the shaft 3, the arm 29 being similarly recessed and bolts Sl-Sl drawing the block 39 and the arm 29 rigidly upon opposite sides of the shaft to seat the shaft in the recesses.

The lower end of the arm 29 is provided with a screw 32 which abuts upon a block 33 bolted to the panel. The screw 32 being adjustable in the arm 29, adjustably stops the arm 29 in the switch open position as shown in Fig. 2, the stationary contact 2 and the movable contact 8 being shown diagrammatically in that figure in the position which they occupy when the switch is open and the parts are in their normal positions.

The arm 29 is constrained to its counter-clockwise normal position illustrated by a spring 34 abutting at one end upon the panel I and at its opposite end abutting upon an adjustable screw stud 35.

As shown in Fig. 11, the stud 35 may be screwed into a cross arm 38 extending laterally from the arm 29 on one side thereof, and secured to the arm by a bolt 31, and extending from the other side of the arm 29 (as shown in dotted line at 38) to constitute the back stop of a pivoted ratchet element 39.

The ratchet element 39 oscillates on a pin 49 driven into the arm 29 and extending therefrom.

A roller 4! is mounted on a pin 42 in a fork on the end of the ratchet element 39, and the ratchet element is constrained to take up a clockwise position with its rearward end, opposite the roller 9!, abutting upon the portion 38 of the cross arm 36 by a spring 43 wound around the end of the pin 48 and anchored thereto and having a free end engaging the underside of the pin 42.

The bracket 5 secured to the panel I, and which supports one of the round ends 9 of the shaft 3, is provided with a vertically spaced pair of upper and lower bosses G4 and 45. In the upper boss 94 is reciprocably supported a plunger 48, the lower end of which is of reduced diameter and reciprocably mounted in the lower boss 45 and constitutes a piston rod having on the lower end thereof a piston 48 reciprocable in a cylinder 49 to be described. Normally the plunger 48 is supported on the lower boss 45 by the shoulder at 58 at the reduction of diameter thereof and the plunger 48 is yieldably held downward on the boss 45 by a spring 5! abutting at its lower end upon the upper end of the plunger and at its upper end abutting upon a spring head 52 adjustably movable up and down by a screw 53 to adjust the compression of the spring 5|, the screw 53 being threaded into the upper end of a standard 54 mounted upon the upper side of the bracket 5.

The plunger 45 is prevented from rotating by a finger 55 secured to the upper portion of the bracket 5 adjacent the upper boss 44 and pro jecting into a groove 58 in the plunger.

A cam 5'! having an inclined cam face 58 is secured to one side of the plunger between the bosses 49 and 45 by a pair of screws 59-59 and if desired, may be adjusted toward and from the plunger by shims 58 disposed between the plunger and the cam.

When the plunger 98 is reciprocated upwardly by means to be described, the cam face 58 will move into engagement with the roller 4| on the arm 29, the arm being adjusted so that the roller will be adjacent to but preferably not touching the cam face, and the roller GI will roll over the cam face 58, and the arm 29 will therefore be rocked clockwise together with the shaft 3 to which it is secured. After the initial part of the movement, the movable switch contact 8 will be carried into engagement with the stationary contact 2 to close the electric circuit. After the cam 51 has moved upwardly sufficiently far, the roller ll will be released and the spring 39 will return the arm 29 counterclockwise, opening the switch contacts 8-2, the arm 29 returning to its normal position illustrated in Fig. 2. At this time, the cam 51 will be above the roller 4!. As the plunger 45 returns downwardly to its normal position, the lower side of the cam 5 will engage the roller but will not be effective to move the switch arm and operate the switch because the roller, being mounted on the ratchet element 39, will rock the ratchet element 7 as shown in Fig. 6 and the cam 51 will pass beyond the roller and then the roller will snap back under the force of the spring 43 to its normal position of Fig. 2, being stopped upon the cross arm 38, as described.

Means to be described supplies fluid pressure at an adjustable rate to the under side of the piston 48 in the cylinder 49 to move the plunger '19 upwardly. If the pressure be supplied at a sufficiently reduced rate, the roller 4| will remain in contact with the cam face 58 throughout the stroke of the plunger and the duration of the current impulse will be determined solely by the speed of the plunger 96 and the length vertically of the cam face 58.

When this mode of operation is desired, and a long current impulse is wanted, a cam such as shown at 6! in Fig. 10 may be utilized having besides the surface 62' which will initially effect the closing of the contact, a surface 63 which will hold the contact closed with little or no further movement during continued movement of the plunger 48.

In other cases, for example when impulses of relatively short duration are wanted, the plunger 98 will move upwardly more rapidly and then the arm 29 will be rocked clockwise with greater velocity and after the cam face 58 has left the roller 4!, the arm 29 will continue in its clockwise direction for a time determined by the inertia of the arm and its associated parts opposed by the spring 34.

To adjust such time intervals, for a given tension of the spring 34, the inertia of the arm 29 and associated parts may be varied by means of a weight 64 secured to the arm 29 by a nut 85 on the screw 32 above referred to, which is threaded into the arm 29; and by means of a slot 58 in the weight 54, it may be moved toward and from the axis of the shaft 3 whereby the kinetic inertia of the arm unit including the weight M'will be varied adjustably.

The arm 29 when in the process of being thrown from the cam 5'! by inertia is illustrated in Fig. 5.

In any case, the rate of acceleration at which the plunger moves upwardly and therefore the time ittakes tocomplete its stroke may be ad J'usted by the spring 34 which also functions to return the plunger downwardly.

After the plunger 46 has been moved upwardly by fluid pressure, it is necessary of course to exhaust the pressure from the cylinder 49under the piston 48 to permit the plunger 46 to return. The means for controlling the admission of fluid under pressure to the cylinder 49 adjustably and to control the exhaust therefrom will now be described.

The cylinder 49 is formed in a cylinder head 61 threaded at its upper end as at 68 whereby it may be screwed into the under side of the lower boss to close the upper end of the cylinder and to-align it with the piston rod 41, and to mount it on the frame bracket 5.

At'the lower end of the cylinder head 6'! is a threaded opening 99 into which a nipple on the end ofthe conduit 28 may be screwed and a duct 70 communicates therewith (see Figs. 12, 8 and 9).

The duct 'Hl'communicates with a cross duct 1| opening downwardly through a short duct '12 into a'valve bore 13 in which reciprocates a piston valve 'l l'oftubular form closed at its upper end and open at its lower end. A spring I5 within the valve abuts at its upper end on the closed end of the valve and holds the valve upwardly to seal the. duct 12, the top of the valve having an annular bead 99 thereon to insure a seal. The lower end of the valve spring 15 abuts'upon the upper end of a tubular screw 76' threaded into the head "i"! of a nipple 78, the skirt of' which is threaded into the lower end of the'bore 13, the tubular screw 16 being locked by a lock nut 19; By adjusting the screw 15, the compression of the spring 15 on the Valve M may be varied.

The valve bore 13'is enlarged to provide an upper and a lower annular chamber 99 and 91 respectively between the ends of the valve M and the valve is provided with one or more ports 82' through the wall thereof which, when the valve is in its normal upper position illustrated, effects communication between the interior of the valve and the lower annular chamber 8|.

The cylinder 49 has a fluid admission duct 83, see Fig. '7, having a valve seat 84 therein and a valve stem 85is threaded as at 86' intothe lower end of thecylinder head fil'and has a needle valve 81 to vary the size of the opening into the duct 83; the shank or upper portion of the valve stem 85 being disposed longitudinally of a bore 88 larger than the shank.

As shown in Fig. 8, a cross duct 89 connects the needle valve bore 38 with the upper annular chamber 89'.

A fluid exhaust duct 99 communicating with the cylinder and extending downwardly therefrom, see Fig. '7, opens into a bore 9! in which is threaded ascrew 92. A ball check valve 93 normally closes the lower end of the duct 99 and is held in' closing position by a spring94, the pressure of' the spring being adjustable by the screw 92.

The lower ends of the bores 88 and 9| are sealed by lock nuts 95 and 96 on the threads of the needle valve 85 and screw 92.

A cross duct 91, see Fig. 9', connects the lower annular chamber 8| with the bore 9!.

A small diameter bleeder duct I90 effects restricted communication of the valve bore 13, at a point above the Valve 14, with the atmosphere. A duct 91 connects the annular chamber 8! with the bore 9| at a point below the valve ball 93.

The above described interior construction of the cylinder head 6'! is shown in Fig. 12 developed for convenience of reference into a single sectional plane; and in fact, it may, if preferred, be constructed as shown in that figure.

In the operation of the valve arrangement in the cylinder head 6"! just described, fluid under pressure enters by the conduit 28 and passing through the ducts '59, H and i2 is shut on. by the seal at the upper end of the valve '54. It is one of the advantages of this invention that the operation of the switch as above described will not occur until the pressure to operate it has reached. a certain predetermined value so that, as a result all operations occur with positiveness. If, as occurs when the device is operated by pressure from a welding gun, as illustrated, the pressure communicated to the cylinder 49 is a rising pressure, the switch operating pressure value in the cylinder 49 is reached irregularly and at one time attained more rapidly or more slowly than at another, so that in one case the switch would be' operated quickly and in another case sluggishly. By the arrangement illustrated,

however, no operation of the switch can occur until the pressure has reached a predetermined value which as will now be understood, is de termined by the tension of the spring 15 holding up the valve M. When however this pressure hasbeen reached, the piston valve M will move downwardly and will first close off the port 82 by moving it into the valve bore 1-3 below the lower annular chamber 8!. The valve will continue to move downwardly until the upper end of the valve moves into the upper annular chamber 99 whereupon the fluid enters this annularichamber'and then flows therefrom through the cross duct 89'to the needle valve bore 88 and thence through the needle valve 84-43? into the cylinder 49'to force upwardly the piston 48 to operate the switch as above described.

It will be observed that the valve 14 seals the upper end of its bore E3; on the bead 99, which is of'smaller diameter than the upper end of the valve. The valve opening pressure is therefore that applied upon a small valve diameter but as soon as'the valve starts to move and breaks the seal at the bead99, the full area of the valve end is exposed. to the operating pressure. Thus a quick snap action of the valve is effected causing it to move instantly to full open position when it starts. In some cases, if the seal at the bead 99 is not perfect, the air under pressure will leak around the bead, and before the pressure has attained the value at which it is desired to operate the switch, such smaller pressure acting on the full area of the valve will operate it, resulting in premature low-pressure-operation of the switch. To avoid these effects of leakage around the bead 99, the said bleeder duct I89 may, if desired, be provided to exhaust the leakage air to atmosphere so that it cannot accumuiate sufliciently to move the'valve.

The time interval during which the switch contacts will remain closed may be adjustably varied accumulation of pressure in by adjusting the needle valve 81, as above referred to, which accordingly adjusts the velocity of the piston 48 and plunger 46.

As stated, the piston valve M prevents admission of operating air to the switch cylinder until the pressure has attained a predetermined amount; so also, similarly, the operating plunger 46 will not be returned to its lower starting position until the fluid pressure has been reduced. This will insure that the operator of the gun l3 will have released the button 26 to allow the air under the gun piston ll to discharge outwardly through exhaust port 98 on the gun which, in turn, insures that the plunger 46 will not return until the electrodes of the gun have been opened. Thus there is no danger that the switch will unintentionally close or repeat.

When, however, the gun button 26 has been released and the gun pressure exhausted at the port 98 thereon, and the supply of fluid pressure from the conduit 22 has thus been cut off, the pressure in the cylinder 59 will be relieved and this reduced pressure being communicated to the upper end of the valve M will permit the spring 15 to move the valve upwardly and the port 82 will then communicate with the lower annular chamber 8i. Thereupon the plunger #6 will fall and the piston 48 will force the fluid downwardly through the duct 99, opening the check valve 93, and into the bore 9|, and thence will flow by duct 91 to the annular chamber 8i and thence through the port or ports 82 into the interior of the valve 14 and thence downwardly through the tubular screw It to the atmosphere.

Thus when the pressure is released, the plunger will return or reset instantly to be in position as soon as possible for another operation, if the ball valve 93 is held lightly against its seat or more slowly it held more firmly against the seat by adjustment of the spring 9 3 by the screw 92. By this means the velocity of return of the piston 48 and the possible frequency of successive operations may be adjusted. In cases in which the needle valve 91 is ad justed for a very slow flow of fluid to the cylinder 49, there may be enough leakage out of the cylinder 49 by way of the duct 99, bore 9|, duct 91, annular chamber 8| and around the piston valve and out through the tubular screw 16, to prevent the cylinder 49 and to interfere with the desired slow movement of the plunger 45. It is to prevent such leakage that the duct llll is provided. This duct communicates the full source pressure to the underside of the ball 93 when the valve 14 has moved down, which holds the ball firmly on its seat and effectively seals the duct 99. In cases in which the needle valve 81 is adjusted for very short time intervals, that is to say, is substantially in a wide open position, the air under the piston may be allowed to exhaust through the duct 83, past the needle valve 87, through the duct 89 into the space above the valve 14, thus holding the valve down, and out through the ducts II and 10. The screw 92 may be in such cases screwed in far enough to cover the duct 9'! and cut off exhaust through the duct 9?. By this means, the piston 48 will reset for another operation only after the gun has fully reset and pressure in the line 28 has thereby been reduced.

Thus, as will be seen, the switch cannot be operated until the pressure for operating it has attained a suitable operating value at which it will operate the switch with a positive action and positively initiate a switch operating time interval; and that this time interval can be widely adjusted for diiferent time periods of current duration through the switch contacts; and that the switch operating plunger will not be reset for another operation until the pressure has been fully released by the release operation at the welding device; and that the operating pressure will not be attained until after the gun or other .device has been fully operated to engage the electrodes with the work; and that unintended repeating of the switch is prevented; and that for any pressure adjustment of the piston valve M by the spring l and any timing by the needle valve 84-81, the current duration may be further adjusted at the spring 34; and also by the inertia weight 64 when the interval is to be short.

Subject matter illustrated and described but not claimed herein constitutes the subject matter of the co-pending applications of Charles H. Rippl, Serial No. 62,795, filed February '7, 1936, for improvements in Welding current control apparatus and of Edward G. Beiderman, Serial No. 84,981, filed June 13, 1936 for improvements in Time controlled electric switches.

I have illustrated the gun electrode mains l6 as receiving electric current directly from the mains 9 when the switch contacts close. It will be understood of course that, in accordance with well known practice, the mains l9 may be connected to the secondary of a transformer, the primary of which is energized from the mains 9 when the contacts of the switch are closed.

It will be understood by those skilled in the art that when pressure is first admitted to the cylinder l6 and expands therein, the pressure in the conduit 23 will be less than full pressure, but will gradually rise; and when the electrodes H and [2 have been engaged and further movement of the piston l1 and further expansion in the cylinder i6 is stopped, the pressure rises in the conduit 28 and duct ill to a high value. It is this rising pressure which is referred to above as applied at the upper end of the valve 14.

My invention is not limited to the exact con struction illustrated and descriped but includes all changes and modifications which may be made therein and mechanical equivalents thereof which come within the scope of the appended claims.

I claim:

1. In a pneumatic apparatus, a unitary housing having therein a fluid pressure cylinder and being adapted to be detachably secured to a mechanism of the type having an operating piston, the piston being in the cylinder when the housing is attached to the mechanism and being movable by fluid pressure therein, an admission passageway in the housing adapted to be connected to a source of fluid pressure and communicating with the cylinder, an exhaust passageway communicating with the cylinder, a valve cylinder in the housing having a skirted trunk piston valve in the valve cylinder the valve having an exhaust port through the skirt communicating with the exhaust passageway and with the interior of the valve and thence with the atmosphere, the valve having a normal position in which it closes the admission passageway and aligns the exhaust port with the exhaust passageway and the valve being subjected to fluid pressure in the admission passageway in the direction to move it to a position in which it opens the admission passageway and covers the exhaust port, and a spring for holding the valve in its normal position against the fluid pressure in the admission passageway.

2. In a valve structure, a valve housing, a fluid pressure inlet duct, a fluid pressure outlet duct, a piston valve cylinder, and a fluid pressure exhaust duct, all disposed in generally parallel relation in the housing, a cross duct connecting the inlet duct with the valve cylinder, a piston valve in the cylinder, means normally yieldably holding it in position to close the inlet duct, a pair of ports, one normally opened by the valve and the other normally closed, a cross duct connecting the normally closed port with the outlet duct, a cross duct connecting the normally opened port with the exhaust duct, and a passageway to atmosphere from the normally opened port.

3. The arrangement described in claim 2 and in which an adjustable valve for varying the size of the outlet duct is provided.

4. The arrangement described in claim 2 and in which the yieldable holding means for the valve is an adjustable spring.

5. In a valve structure, a valve housing, a fluid pressure inlet duct, a fluid pressure outlet duct, a piston valve cylinder, a fluid pressure exhaust duct, all disposed in generally parallel relation in the housing, a cross duct connecting the inlet duct with the valve cylinder, a piston valve in the cylinder, a spring normally yieldably holding the valve in position to close the inlet duct, a pair of ports one normally opened by the valve and the other normally closed by the valve, a cross duct connecting the normally closed port with the outlet duct, a cross duct connecting the normally opened port with the exhaust duct, a passageway to atmosphere from the normally opened port, an adjustable valve for varying the size of the outlet duct, a conduit connection with the inlet duct adapted to be connected to a source of fluid pressure, the conduit connection, valve, ad-

justing means, and spring adjusting means all being disposed adjacent to each other on an outer portion of the housing.

6. The arrangement described in claim 2 and in which the exhaust duct is normally closed by a check valve and a cross duct communicates fluid pressure from the normally closed port, when opened, to the check valve in the direction to hold it closed.

7. A servo-motor for operating an apparatus comprising a reciprocable element and a piston for reciprocating it, a main frame, a housing on the frame, an outwardly open inwardly closed main cylinder in the housing for the piston, and outwardly open inwardly closed valve cylinder in the housing, a hollow skirted trunk piston valve reciprocable in the valve cylinder and interiorly communicating with the atmosphere, a fluid pressure supply duct opening through a supply port into the closed end of the valve cylinder the port being normally closed by one end of the Valve, a spring holding the valve normally in supply port closing position against the fluid pressure in the supply duct, a fluid pressure admission duct communicating with the main cylinder and with the valve cylinder at a point inwardly of the supply port closing end of the valve and normally covered by the body of the valve and opened upon movement of the valve effected by pressure in the supply dnct above a predetermined value, an exhaust passageway communicating with the main cylinder and communicating with the valve cylinder, an exhaust port extending through the skirt of the valve, the exhaust passageway normally communicating with the exhaust port and being closed by the valve upon said pressure effected movement of the valve.

CHARLES H. RIPPL.

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